As one of standards of communication systems for providing mobile communication services, long term evolution (LTE) is known. A network related to LTE includes a core network and a wireless network. The wireless network is formed by wireless base stations (each expressed as an “eNB”: hereinafter, also each expressed as a “base station”) directly coupled to the core network.
Each of the base stations is coupled to a control device (mobility management entity: MME) of a base station forming the core network, via an interface called an S1 interface. In addition, base stations are coupled to each other via an interface called an X2 interface. As methods used by a terminal under control of a base station for being handed over to a cell (adjacent cell) generated by a base station (adjacent base station) adjacent to another base station, there are two methods. One is a handover performed via the MME serving as a control device of the base station and is called an S1 handover. The other is a handover performed directly (via no MME) between base stations and is called an X2 handover.
In recent years, the popularization of smartphones or the like causes a traffic amount to rapidly increase. In order to secure a communication capacity corresponding to a demand for a traffic amount, installation of a small-size base station whose transmission power is smaller than an existing base station is considered. The small-size base station is called a femto base station, and a cell formed by the femto base station is called a femtocell. The cell radius of the femtocell is smaller than that of a cell formed by the existing base station. Therefore, the existing base station is called a macro base station, and a cell formed by the macro base station is called a macrocell. The femtocell is locally installed in a private house, an office, a shop, or the like and is coupled to the core network via an access network. The femto base station is also called a “Home eNB”.
In a case where the macro base station is installed, the environment of an installation location is researched in advance, and the information of an adjacent cell is registered as system data of the macro base station. In installation of the femto base station, the detailed information of an adjacent cell may be added to, for example, configuration information of a network, called configuration management (CM) data.
However, the femto base station has portability, and a network environment surrounding the femto base station fluctuates in accordance with an installation location. Therefore, in the femto base station, minimum information is statically set as the CM data, and unconfigured information is collected from an adjacent cell or a wireless terminal (called a user equipment (UE): hereinafter, also expressed as a “terminal”).
As examples of the related art, Japanese Laid-open Patent Publication No. 2009-044336, Japanese National Publication of International Patent Application No. 2012-531865, and, 3GPP TS 36.331 v 12.4.1 (2014-12), 6.3.1 are known.